manacher马拉车

#include<iostream>
#include<algorithm>
#include<cstring>
using namespace std;

char ss[110005],s[220010];
int p[220010];

int init()
{
    s[0]='$'; s[1]='#';
    int g=2;
    for(int i=0;ss[i]!='';i++)
    {
        s[g++]=ss[i];
        s[g++]='#';
    }
    s[g]='';
    return g; //·µ»Ø³¤¶È
}
int manacher()
{
    int len =init();
    int maxlen =-1;

    int id;
    int mx= 0;

    for(int i=1;i<len;i++)
    {
        if(i<mx) p[i]=min( p[2*id-i], mx-i);
        else p[i]=1;

        while(s[i-p[i]] == s[i+p[i]] )
            p[i]++;

        if(i+p[i] > mx)
        {
            id=i;
            mx=p[i]+i;
        }
        maxlen=max(maxlen,p[i]-1);
    }
    return maxlen;

}

int main()
{
    ios::sync_with_stdio(false);
    while(cin>>ss)
    {
        int res=manacher();
        cout<<res<<endl;
    }
}